Association of the DRD4 exon III and 5-HTTLPR VNTR polymorphisms with substance abuse in Jordanian Arab population

Investigating CHRNA5, CHRNA3, and CHRNB4 variants in the genetic landscape of substance use disorder in Jordan

BACKGROUND

Substance use disorder (SUD) is a complex illness that can be attributed to the interaction between environmental and genetic factors. The nicotinic receptor gene cluster on chromosome 15 has a plausible association with SUD, particularly with nicotine dependence.

METHODS

This study investigated 15 SNPs within the CHRNA5, CHRNA3, and CHRNB4 genes. Sequencing was used for genotyping 495 Jordanian males with SUD and 497 controls matched for age, gender, and descent.

RESULTS

Our findings revealed that none of the tested alleles or genotypes were correlated with SUD. However, our analysis suggests that the route of substance use was linked to rs1051730 (P value = 0.04), rs8040868 (P value = 0.01) of CHRNA3, and rs16969968 (P value = 0.03) of CHRNA5. Additionally, a correlation was identified between rs3813567 of the CHRNB4 gene and the age at substance use onset (P value = 0.04).

CONCLUSIONS

Variants in CHRNA5, CHRNA3, and CHRNB4 may interact with SUD features that can influence the development and progression of the disorder among Jordanians.

DRD4 Exon 3 Gene Polymorphisms in Patients Diagnosed with Polysubstance Use Disorder and Co-Occurrence of a Depressive Episode

Background: There has been a noticeable and systematic growth of the use of psychoactive substances over the past few decades. Dual diagnosis is a clinical term referring to the occurrence of psychoactive substance use disorder comorbid with another psychiatric disorder in the same person. The most common type of dual diagnosis is the co-occurrence of alcohol use disorder and mood disorders in the form of a depressive episode. Co-occurrent substance use disorders are frequently influenced by genetic factors. In selecting our area of research, we focused on dopamine and the DRD4 (Dopamine Receptor D4) gene polymorphism as well as associations with personality features. The aim of the study: The aim of the study was to compare DRD4 exon 3 (DRD4 Ex3) gene polymorphisms in patients diagnosed with polysubstance use disorder and co-occurrence of a depressive episode to DRD4 exon 3 gene polymorphisms in patients diagnosed with polysubstance use disorder and without co-occurrence of a depressive episode and a group of healthy volunteers. The study also aimed at establishing associations between personality features and DRD4 exon 3 gene polymorphisms of male patients diagnosed with polysubstance use disorder with co-occurrence of a depressive episode which may present a specific endophenotype of this group of patients. Methods: The study group comprised 602 male volunteers: patients diagnosed with polysubstance use disorder comorbid with a depressive episode (PUD MDD) (n = 95; mean age = 28.29, standard deviation (SD) = 7.40), patients diagnosed with polysubstance use disorder (PUD) (n = 206; mean age = 28.13, SD = 5.97), and controls (n = 301; mean age = 22.13, SD = 4.57). The patients and control subjects were diagnosed by a psychiatrist using the Mini International Neuropsychiatric Interview (MINI), the NEO Five-Factor Personality Inventory (NEO-FFI), and the State-Trait Anxiety Inventory (STAI) questionnaires. An analysis of the DRD4 exon 3 polymorphism was performed. Results: The patients diagnosed with PUD MDD compared to the control group of healthy volunteers showed significantly higher scores on both the STAI status and features scale and the NEO-FFI Neuroticism and Openness Scale, as well as lower scores on the Extraversion, Agreeableness, and Conscientiousness NEO-FFI scales. In the DRD4 exon 3 gene polymorphism, the s allele was more frequent in the PUD MDD compared to the l allele, which was less frequent. The results of the 2 × 3 factor analysis of variance (ANOVA) in patients and controls and the variant DRD4 exon 3 interaction were found on the Extraversion Scale and the Conscientiousness Scale of the NEO-FFI. Conclusions: The associations show that psychological factors combined with genetic data create a new area of research on addiction, including the problem of dual diagnosis. However, we want to be careful and draw no definite conclusions at this stage of our research.

Association of DRD4 exon III and 5-HTTLPR VNTR genetic polymorphisms with psychiatric symptoms in hemodialysis patients

Mental illness is prevalent among hemodialysis (HD) patients. Given that the dopaminergic and serotonergic pathways are involved in the etiology of psychiatric disease, this study evaluated the genetic association of dopamine D4 receptor (DRD4) and serotonin transporter (SLC6A4) genes with psychiatric symptom susceptibility among HD patients. Hospital Anxiety and Depression Scale (HADS) was used to assess anxiety and depressive symptoms among patients (n = 265). Genetic polymorphisms of DRD4 (48 bp VNTR) and SLC6A4 (5-HTTLPR VNTR and rs25531) were examined using a conventional polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique, as appropriate. Significant differences were observed in the distribution of 5-HTTLPR genotypes, SLC6A4 tri-allelic-phased genotype, and DRD4-Exon III VNTR genotypes/alleles between patients with anxiety symptoms versus those with normal/borderline conditions (p<0.05). Binary logistic regression analyses showed that the heterozygous 4,5 VNTR genotype of DRD4 was associated with a higher risk of anxiety symptoms after adjusting for other covariates (odds ratio = 4.25, p = 0.028). None of the studied polymorphisms was linked to depression in HD patients. Collectively, the current findings provide genetic clues to psychopathology in HD patients and suggest that the DRD4 exon III VNTR polymorphism is involved in the etiology of anxiety in this patient population.

Genetic susceptibility of opioid receptor genes polymorphism to drug addiction: A candidate-gene association study

BACKGROUND

Like other complex diseases including drug addiction, genetic factors can interfere with the disease. In this study, three opioid genes (OPRM1, OPRD1, and OPRK1) were examined for an association with drug addiction among Jordanian males.

METHODS

The study involved 498 addicts, in addition to 496 healthy controls and all from Arab descent.

RESULTS

The findings in this study showed that rs1799971 of the OPRM1 gene was in association with drug addiction for both alleles and genotypes with P-values = 0.002 and 0.01, respectively. In addition, a significant association between the dominant model (A/A vs G/A-G/G) of rs1799971 (OPRM1) and drug addiction (P-value = 0.003, OR = 1.59 (1.17-2.15)) was detected. Moreover, a genetic haplotype (AGGGCGACCCC) of theOPRM1 gene revealed a significant association with drug addiction (P-value = 0.01, OR = 1.56 (1.15-2.12)). We also found that the age of addicts, smoking, and marital status with genetic variants within OPRM1, OPRD1, and OPRK1 genes may be implicated in drug addiction risk.

CONCLUSION

We propose that rs1799971 of the OPRM1gene is a genetic risk factor for drug addiction among Jordanian males.

DRD4, DRD2, DAT1, and ANKK1 Genes Polymorphisms in Patients with Dual Diagnosis of Polysubstance Addictions

Background: Approximately 25–50% of people diagnosed with substance use disorder experience psychiatric disorders, and this percentage is even higher if subclinical psychopathological symptomatology is taken into consideration. ”Dual diagnosis” implies the comorbidity of two disorders (mental disorder and addiction), but in a clinical setting, numerous dual diagnoses involve multiple addictions (polysubstance use means the concurrent use of more than one psychoactive substance). Clinical observations and epidemiological studies showed that the use of stimulants in combination with other substances results in additional risks. Apart from the clinical significance of the specificity of stimulants used in combination with other substances, only non-exhaustive research on the specificity of this comorbidity has been performed to date. The aim of the study was to analyze polymorphisms of the genes (DRD4 VNTR in exon III Ex3, DRD2 rs1076560, rs1800498, rs1079597, rs6276, as well as in the PROM promoter region (rs1799732, ANKK1 Tag1A rs1800497, DAT) in a group of patients diagnosed with polysubstance use disorder, including addiction to stimulants, and the co-occurrence of specific mental disorders in a group of patients diagnosed with polysubstance use disorder, including addiction to stimulants, compared to the group of patients diagnosed with polysubstance use disorder. Methods: The study group consisted of 601 male volunteers with psychoactive substance dependence (n = 300) and non-dependent controls (n = 301). The genomic DNA was extracted from venous blood using standard procedures. Genotyping was conducted with the real-time PCR method. All computations were performed using STATISTICA 13. Results: Psychotic disorders were significantly more common in the group of males with polysubstance addiction, including addiction to stimulants, compared to the group of males with polysubstance addiction without addiction to stimulants. In our own research, different statistical significances were found in the frequency of the DRD4 Ex3 gene polymorphism: s/s was more common in the study group. Psychotic disorders were more common in people addicted to stimulants compared to people addicted to other substances. Conclusions: In our study, psychotic disorders occurred more frequently in the study group of patients with polysubstance addiction, including addiction to stimulants, compared to the control group of patients with polysubstance addiction, but with no addiction to stimulants. Different statistical significances were found in the frequency of the DRD4 Ex3 gene polymorphism: s/s was more common in the study group, while the l/l genotype was less frequent in the study group. In DRD2 PROM rs 1799732, the del allele occurred more often than the ins allele in the study group. In the DRD4 Ex3 gene polymorphism, the s allele was more common in the study group, and the l allele was less frequent. In the DRD4 Ex3 gene polymorphism for the s/s genotype, psychotic disorders and generalized anxiety were more common, while for the s/l and l/l genotype, they were less frequent. The DRD4 Ex3 polymorphism s alleles were more common for depressive episode, dysthymia, and psychotic disorders as well as generalized anxiety disorder. We see a clear genetic aspect here. However, we want to be careful and draw no definite conclusions.

Pharmacogenomic landscape of VIP genetic variants in Jordanian Arabs and comparison with worldwide populations

The pharmacogenomics has lately become a focal field of research that investigates the influence of genetic variations of drug-metabolizing enzymes and their receptors and downstream proteins on the interindividual variability in response to medications and adverse drug reactions. Therefore, it is significantly important to study and analyze the variations in drug response between different ethnic groups and populations. The current study aimed to detect the distribution of the genotype and allele frequencies in several very important pharmacogenetic (VIP) gene polymorphisms in the Jordanian population of Arab descent. This study involved 500 unrelated Jordanian individuals of Arab descent. A total of 65 VIP variants located within 33 candidate genes were randomly selected from the PharmGKB database and genotyped using the MassARRAY (iPLEX GOLD) system. The chi-square test was used to evaluate the significant differences of minor allele and genotype frequencies between the Jordanian and other populations including CHE, ASW, CEU, CHB, CDX, GIH, GBR, JPT, LWK, MXL, TSI, YRI, CAR, and ACB. This study revealed six variants were not in Hardy Weinberg equilibrium (HWE) (P-value > 0.05) and ten SNPs showed monomorphic features. Most of the remaining forty-nine variant frequencies were significantly different from the compared ethnic groups (P-value < 0.05). The results of this study may be helpful to develop safer treatment by applying the concept of personalized medicine based on the profile of VIP pharmacogene variants of the Jordanian population of Arab descent.